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UNITED STATES PATENT Fries.

JOHN C.-I\IONTGO1\IERIE, OF DALMORE, STAIR, SCOTLAND.

EXTRACTION OF GOLD AND SILVER FROM ORES.

SPECIFICATION forming part of Letters Patent No. 549?? 36, datedNovember 12, 1895.

Application filed March 20,1894. Serial No. 504,443. (No specimens.)Patented in England October 2'7, 1893, No 20,343 in New Zealand October27, 1893, No. 6,775; in Cape Colony March 29, 1894, No. 913; in IndiaMarch 29, 1894, N0. 106; in SouthAustraliaA ril 9, 1894,110. 2,663; inWest-Australia A ri110,1894,N0.502; inViotoria April 10, 1894, No.11,265; inTransvaalApril 10, 1894, N0. 620; inNew SouthWales April 12,1894, No. 4,972; in Tasmania April 14, 1894,N0. 1,261;

- in Canada July 20, 1894, No. 46,630, and in Austria-Hungary July 24,1894,11'0. 1'72 and No. 6,627.

To all whom it may concern:

Be it known that 1, JOHN CUNINGHAME MONTGOMERIE, a subject of the Queenof Great Britain, residing at Dalmore, Stair, in the county of Ayr,Scotland, have invented certain new and useful Improvements in theExtraction of Gold and Silver from Ores or Compounds Containing theSame, (for which I have received the following Letters Patent: in GreatBritain, dated October 27, 1893, No. 20,343; in Austria-Hungary, datedJuly 24, 1894, No. 172 and No. 6,627; in Canada, dated July 20, 1894,No. 46,630; in Cape Colony, dated March 29, 1894, No. 913; in Transvaal,dated April 10, 1894, No. 620; in India, dated March 29, 1894, N o. 106;in South Australia, dated April 9, 1894,- No. 2,663; in West Australia,dated April 10, 1894, No. 502; in Victoria, dated April 10, 1894, No.11,265; in

New South WVales, dated April 12, 1894, No. 4,972; in New Zealand, datedOctober 27, 1893, No. 6,775, and in Tasmania, datedApril 14, 1894, No.1,261,) of which the following is a specification.

This invention relates to the treatment of auriferous and argentiferousores or compounds for the purpose of separating and collecting the goldor silver or gold and silver contained therein and to means forrendering the solution, after undergoing filtration, comparatively freefrom muddy particles.

According to myinvention I treat in a vessel containing water the orewith a cyanide, an alkaline oxide, a nitrate or a nitrite, and anoxidizing agentsuch as an alkaline dioxide or air, oxygenated air, oroxygen.

In applying my improvements to the treatment of ores containing gold orsilver or gold and silver I crush or grind the ore sufficiently fine toadmit of its passing through a sieve of from forty to ninety meshes tothe lineal inch, according to the nature of the ore. Preferably I thenadd to the ore, while in a solid state, from one-half pound to twopounds or more, as circumstances demand, of sodium dioxide or otheralkaline dioxide and charge the same into a barrel containing water andclose the inlet. The pulverized ore mixed with the dioxide is treated inthe barrel or vessel, along with the water, which is in sufficientquantity to render the mixture of the consistency of cream or very thinmud, with the following chemicals: (a) a cyanide, such as cyanide ofpotassium or of sodium or of other such cyanide or mixture of cyanides;(b) an alkaline oxide, such as sodium oxide or its hydrate (causticsoda) or other alkaline oxide or a hydrate of an alkaline oxide, and (c)a nitrate or nitrite, such as nitrate of soda or of potash or of ammoniaor other suitable or equivalent nitrate or nitrite. The barrel,containing the ore, the dioxide, and the other chemicals above referredto, is then revolved for a short time in order to thoroughly mix itscontents. The barrel is then charged with air or oxygenated air or (whensodium dioxide is not used) with oxygen to a pressure of from fifty toone hundred pounds per square inch. WVhen oxygen is used, sodium is notrequired.

\Vith some ores when sodium dioxide is employed, air or oxygen underpressure is not needed. In such case the ore may be treated in tanks,with or without agitation.

hen there is no agitation, it is preferable to allow the solvent liquidto percolate through the mass of ore repeatedly, the liquid as it passesaway being fed back to the surface of the ore until the precious metalsare sufficiently dissolved. Under such procedure the sodium dioxide,instead of being mixed with the ore, may be dissolved in the solventsolution in very small quantities at a time, so as to prevent anyviolent action or great loss of oxygen occurring. By way of example, arefractory ore of a muddy character containing eight ounces of gold andfifty ounces of silver per ton maybe treated with ten pounds of cyanideof potassium, ten pounds of caustic soda, and seven pounds of nitrate ofsoda, with one and one-half pounds of sodium dioxide added to the ore.These proportions should, however, be varied considerably with difierentdescriptions of ore, the most suitable proportions being readilydetermined by experiment. Should the other chemicals mentioned beemployed, the same proportions may be used. The barrel is then againrevolved, and maintained in motion until the precious metals aredissolved, with average ores the time occupied being from four to sixhours. The barrel is thereupon emptied, the contents filtered andwashed, and the solution treated in any known manner for the separationof the precious metals.

An important advantage resulting from the use of a nitrate or nitrite,as hcreinbefore described, is that the liquid filtered from the tailingsis tolerably free from muddy particles, any matter left in suspensionsettling quickly, so that charcoal, if and when employed as aprecipitant,is not liable to become choked by sediment.

I have found with many ores that when cyanide alone is used the liquidis very muddy and takes weeks or even months to settle, whereas asolvent solution containing a nitrate or nitrite becomes fairly clearin, a day or so after filtration from the tailings.

In treating the liquid received from the filters and containing theprecious metals in solution, as also the unused solvent and otherchemical agents employed, I prefer to pass the said liquid through afilter containing charcoal, preferably wood-charcoal, or through aseries of such filters.

I wish it understood that I claim as within the scope of my inventionthe chemical equivalents of the substances herein specificallymentioned, and when I specify in the claims the use of a nitrate I meanto also include a nitrite. \Vhen I specify the use of oxygen, I

include also the use of oxygenated air or air, and when an alkalineoxide is mentioned it should be understood that its hydrate may besubstituted.

Sodium dioxide must be understood to include its equivalent alkalinedioxide.

I claim as my in vention 1. The improved process ofextracting gold andsilver from ores or compounds containing the same, substantially asherein described, consisting in treating the ore in a vessel containingwater, with a cyanide, an alkaline oxide, a nitrate and an oxidizingagent.

2. The improved process of extracting gold an d. silver from ores orcompounds containing the same, substantially as herein described,consisting in mixing with the pulverizedv ore or compound, an alkalinedioxide, such as sodium dioxide, and treating this mixture in a vesselcontaining water holding in solution a cyanide, such as cyanide ofpotassium, an alkaline oxide, such as sodium oxide and a nitrate, suchas sodium nitrate, allowing the chemicals to act on the ore until theprecious metals are sufliciently dissolved.

The improved process of extracting gold and silver from ores orcompounds containing the same, substantially as herein described,consisting in mixing with the pulverized ore or compound, an alkalinedioxide, such as sodium dioxide, charging the mixture into a lntrrel orvessel. containing Water, holdin in solution a cyanide, such aspotassium cyanide, an alkaline oxide, such as sodium oxide, and anitrate, such as sodium nitrate, closing the barrel or vessel andforcing in an oxidizing agent, such as air, the contents being thenagitated until the precious metals are suiliciently dissolved.

JOHN C. llIONlGOMERIE.

\Vitnesses:

F. J. RAPSON, W. F. CAIN.

